Once more, with feeling: not all VSIs have rings. To assume so is to
invite null pointers to your party.

Change-ID: I576858824468d9712d119fa1015a1f28c27712c4
Signed-off-by: Mitch Williams <mitch.a.williams@intel.com>
Signed-off-by: Jeff Kirsher <jeffrey.t.kirsher@intel.com>